Such handheld power tools often have a reduction gear unit for driving a drive shaft, using which a predefined motor speed may be reduced to a speed range of the drive shaft which is necessary for a particular application. For example, motor speeds of approximately 20,000 RPM are reduced to a speed range of approximately 150 RPM to 2,000 RPM in cordless screwdrivers, cordless combi drills, and/or cordless percussion drills. The reduction gear units are, for example, designed as multistage planetary gear sets having at least two gears, so that a user of such a handheld power tool is, for example, able to shift this handheld power tool between a first, slower, gear having a comparatively high torque and a second, faster, gear having a comparatively low torque. Moreover, the reduction gear unit may be assigned a torque clutch using which it is possible to prevent the drive shaft from being driven by the reduction gear unit during operation of the handheld power tool, if a torque, transferred from the drive shaft to the reduction gear unit, exceeds a threshold value settable by a user.
The disadvantage of the above-described power drills is that in the case of cordless combi drills, the torque clutch or a clutch functionality provided by the torque clutch is deactivated in the drilling mode, thus setting the threshold value settable by the user virtually to “infinitely.” If, however, the cordless combi drill set to the drilling mode is used for screwing, a kinetic energy of rotation conveyed to the drive shaft may be converted into a rotation of the cordless combi drill or a tool housing assigned thereto, for example, in the event of so-called hard screw applications which may occur during metal screw fittings, for example, and may cause a spontaneous blocking of the drive shaft. This may result in an impact-like load on components of a drive train assigned to the cordless combi drill and in a failure of the components of the drive train involved.